Control system and control strategy for reducing urea injection crystallization clogging

Abstract

The application discloses a control system and control strategy for reducing urea injection crystallization blockage, comprising: a liquid outlet of a urea tank is communicated with a liquid inlet of a urea pump through a liquid inlet pipe, and the urea pump draws urea solution from the urea tank through the liquid inlet pipe; a nozzle is communicated with a liquid outlet of the urea pump through a jet pipe, and the urea pump can deliver urea solution to the nozzle for injection through the jet pipe; a liquid return pipe is arranged between a liquid return port of the urea pump and a liquid return port of the urea tank; wherein the urea pump has a back suction function, residual urea solution in the nozzle can be sucked back into the urea pump through the back suction function of the urea pump through the jet pipe, and then the residual urea solution is delivered back to the urea tank through the liquid return pipe; an ECU controller is electrically connected with the urea pump, the urea tank and the nozzle, and the ECU controller can control the specific actions of the urea pump, such as liquid suction from the urea tank, liquid delivery to the nozzle, liquid return to the urea tank and graded back suction from the nozzle. The problem of crystallization caused by high-temperature evaporation of urea solution can be prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engine design and manufacturing, and in particular, to a control system and control strategy for reducing urea injection crystallization blockage. BACKGROUND

[0002] With the upgrading of emission regulations, diesel engines generally use high-efficiency SCR (selective catalytic reduction technology) to reduce NOx emissions in exhaust gas, but with the application of urea injection system, nozzle crystallization failures occur frequently, and the rationality of urea injection strategy has a greater impact on nozzle crystallization. A reasonable urea injection strategy can greatly reduce the risk of urea crystallization.

[0003] The control strategy of the prior art generally uses a complete backflow control after the injection system completes the injection command, so that the urea solution in the injection pipe flows back to the urea tank, but the prior art cannot well solve the problem of frequent failures caused by nozzle crystallization due to the irrationality of the urea injection strategy.

[0004] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the background of the present application and should not be taken as admitting that such information in the prior art, which is known by those of ordinary skill in the art. SUMMARY

[0005] The present application aims to provide a control system for reducing urea injection crystallization blockage, which can prevent urea solution from evaporating and crystallizing at high temperatures and blocking the nozzle through hierarchical control of urea injection backflow.

[0006] Another object of the present application is to provide a control strategy for reducing urea injection crystallization blockage, which can control the backflow of urea injection according to the specific situation of the vehicle, thereby preventing urea solution from evaporating and crystallizing at high temperatures and blocking the nozzle.

[0007] To achieve the above object, the application provides a control system for reducing urea injection crystallization blockage, comprising a urea pump, a urea tank, a nozzle, a liquid return pipe and an ECU controller; the liquid outlet of the urea tank is communicated with the liquid inlet of the urea pump through a liquid inlet pipe, and the urea pump extracts urea solution from the urea tank through the liquid inlet pipe; the nozzle is communicated with the liquid outlet of the urea pump through an injection pipe, and the urea pump can deliver urea solution to the nozzle for injection through the injection pipe; the liquid return pipe is arranged between the liquid return port of the urea pump and the liquid return port of the urea tank; wherein the urea pump has a reverse suction function, the residual urea solution in the nozzle can be sucked back into the urea pump through the reverse suction function of the urea pump through the liquid injection pipe, and then the residual urea solution is delivered back to the urea tank through the liquid return pipe; the ECU controller is electrically and data-connected with the urea pump, the urea tank and the nozzle, and the ECU controller can control the specific actions of the urea pump, such as liquid suction from the urea tank, liquid delivery to the nozzle, liquid return to the urea tank and graded reverse suction from the nozzle.

[0008] In a preferred embodiment, the control system for reducing urea injection crystallization blockage further comprises an engine can bus which is electrically and data-connected with the ECU controller, and the ECU controller receives information of the engine through the engine can bus, and according to the injection demand of the engine, monitors the state of the urea tank and issues injection instructions to the urea pump and the nozzle to perform injection actions.

[0009] To achieve another object, the application further provides a control strategy for reducing urea injection crystallization blockage, which is completed by the control system as described above, and the control strategy comprises: the ECU controller obtains the demand of the engine through the engine can bus, and the ECU controller issues execution injection instructions to the injection pump and the nozzle according to the demand; and when the injection pump and the nozzle do not receive injection instructions or have completed the injection instructions, the judgment of entering the reverse suction work and the waiting instruction state are entered.

[0010] In a preferred embodiment, the control strategy further comprises a control logic step of judging whether to enter the graded reverse suction: according to the running characteristics or use scenarios of the vehicle, some intermittent vehicles are not entered into the graded reverse suction strategy, and after a complete reverse suction strategy is completed in 60s, the waiting instruction state of stopping work is entered.

[0011] In a preferred embodiment, the control strategy further comprises: after the control logic of entering the graded reverse suction is judged according to the running characteristics or use scenarios of the vehicle, a temperature judgment step is entered, when the environmental temperature is lower than-5℃, the complete reverse suction strategy is executed, the reverse suction time is 60s, the residual urea is prevented from freezing at low temperature, the heating thawing effect is affected, and even the injection device is damaged, and after the complete reverse suction strategy is completed, the waiting instruction state of stopping work is entered.

[0012] In a preferred embodiment, the control strategy further comprises: when entering the control logic of the hierarchical backflow according to the running characteristics or use scenarios of the vehicle, entering the temperature judgment step, when the ambient temperature is higher than -5℃ and lower than 30℃, further judging whether the ambient temperature is lower than 150℃, when the temperature is lower than 150℃, executing the complete backflow strategy, and the backflow time is 60s, preventing the urea solution from evaporating and blocking the nozzle in the high temperature condition.

[0013] In a preferred embodiment, the temperature judgment step of the control strategy further comprises: when the exhaust temperature is greater than 150℃, executing the incomplete backflow strategy, and the backflow time is 20s, and entering the waiting instruction state of stopping working after completing the above backflow strategy.

[0014] In a preferred embodiment, the control strategy further comprises: when entering the control logic of the hierarchical backflow according to the running characteristics or use scenarios of the vehicle, entering the temperature judgment step, when the ambient temperature is higher than 30℃, further judging whether the ambient temperature is lower than 150℃, when the temperature is lower than 150℃, executing the complete backflow strategy, and preventing the urea solution from evaporating and blocking the nozzle in the high temperature condition.

[0015] In a preferred embodiment, the control strategy further comprises: when entering the control logic of the hierarchical backflow according to the running characteristics or use scenarios of the vehicle, entering the temperature judgment step, when the exhaust temperature is greater than 150℃, executing the incomplete backflow strategy, and the backflow time is 10s, and entering the waiting instruction state of stopping working after completing the above backflow strategy.

[0016] Compared with the prior art, the control system and control strategy for reducing urea injection crystallization blockage have the following beneficial effects: the scheme is suitable for all engines using urea injection devices, hierarchical backflow control strategies are realized according to different vehicle uses, different ambient temperatures and different exhaust temperature states, good operability is achieved, a new method for reducing urea crystallization risk is provided, a part of urea is reserved in the urea pipe in the high temperature condition, that is, incomplete backflow is realized by reducing the backflow time, urea solution evaporation (high temperature) is prevented, and crystallization and nozzle blockage are prevented, the backflow control strategy is based on different application characteristics of the vehicle, ambient temperature and exhaust temperature, and the optimization purpose is achieved through the hierarchical backflow strategy. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the device arrangement of the control system according to an embodiment of the application;

[0018] Figure 2 is a control logic schematic diagram of the control strategy according to an embodiment of the application. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0020] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0021] like Figure 1 As shown, a control system for reducing urea injection crystallization blockage according to a preferred embodiment of the present invention includes a urea pump, a urea tank, a nozzle, a return pipe, and an ECU controller. The outlet of the urea tank is connected to the inlet of the urea pump through an inlet pipe, and the urea pump draws urea solution from the urea tank through the inlet pipe. The nozzle is connected to the outlet of the urea pump through a spray pipe, and the urea pump can deliver urea solution to the nozzle for injection through the spray pipe. The return pipe is located between the return port of the urea pump and the return port of the urea tank. The urea pump has a backflow function, and residual urea solution in the nozzle can be drawn back into the urea pump through the spray pipe by the backflow function of the urea pump, and then transported back to the urea tank through the return pipe. The ECU controller is electrically and data connected to the urea pump, the urea tank, and the nozzle, and the ECU controller can control the specific actions of the urea pump in drawing liquid from the urea tank, delivering liquid to the nozzle, returning liquid to the urea tank, and performing staged backflow from the nozzle.

[0022] In a preferred embodiment, the control system for reducing urea injection crystallization blockage further includes an engine CAN bus, which is electrically and data-connected to the ECU controller. The ECU controller receives engine information through the engine CAN bus, and based on the injection requirements proposed by the engine, monitors the status of the urea tank and issues injection commands to the urea pump and nozzles to perform injection actions.

[0023] like Figure 2 As shown, a control strategy for reducing urea injection crystallization blockage according to a preferred embodiment of the present invention is implemented through a control system as described above. The control strategy includes: the ECU controller obtains the engine's requirements through the engine CAN bus; the ECU controller issues injection commands to the injection pump and nozzle as needed; and when the injection pump and nozzle do not receive injection commands or have already completed injection commands, they enter a judgment and waiting command state for back suction operation.

[0024] In some implementations, the control strategy also includes a control logic step to determine whether to enter the graded back suction: based on the vehicle's operating characteristics or usage scenario, for some intermittently used vehicles, the graded back suction strategy is not entered, and after completing a full back suction strategy in 60s, the vehicle enters a waiting command state to stop working.

[0025] In some embodiments, the control strategy further comprises: when entering the control logic of the hierarchical back-suction according to the running characteristics or use scenarios of the vehicle, entering a temperature judgment step, when the ambient temperature is lower than -5℃, executing a complete back-suction strategy, and the back-suction time is 60s, preventing the residual urea from freezing at low temperature, affecting the heating thawing effect, and even damaging the injection device, and entering a waiting instruction state of stopping working after completing the complete back-suction strategy.

[0026] In some embodiments, the control strategy further comprises: when entering the control logic of the hierarchical back-suction according to the running characteristics or use scenarios of the vehicle, entering a temperature judgment step, when the ambient temperature is higher than -5℃ and lower than 30℃, further judging whether the ambient temperature is lower than 150℃, when the temperature is less than 150℃, executing a complete back-suction strategy, and the back-suction time is 60s, preventing the urea solution from evaporating under high temperature and blocking the nozzle.

[0027] In some embodiments, the temperature judgment step of the control strategy further comprises: when the exhaust temperature is greater than 150℃, executing an incomplete back-suction strategy, and the back-suction time is 20s, and entering a waiting instruction state of stopping working after completing the above back-suction strategy.

[0028] In some embodiments, the control strategy further comprises: when entering the control logic of the hierarchical back-suction according to the running characteristics or use scenarios of the vehicle, entering a temperature judgment step, when the ambient temperature is higher than 30℃, further judging whether the ambient temperature is lower than 150℃, when the temperature is less than 150℃, executing a complete back-suction strategy, and preventing the urea solution from evaporating under high temperature and blocking the nozzle.

[0029] In some embodiments, the control strategy further comprises: when entering the control logic of the hierarchical back-suction according to the running characteristics or use scenarios of the vehicle, entering a temperature judgment step, when the exhaust temperature is greater than 150℃, executing an incomplete back-suction strategy, and the back-suction time is 10s, and entering a waiting instruction state of stopping working after completing the above back-suction strategy.

[0030] In summary, the control system and control strategy for reducing urea injection crystallization blockage have the following advantages: the scheme is suitable for all engines using urea injection devices, different vehicles have different purposes, different ambient temperatures, and different exhaust temperature states, hierarchical back-suction control strategies are realized, and good operability is achieved, a new method is proposed for reducing the risk of urea crystallization; at a higher temperature, a part of urea is retained in the urea pipe, that is, incomplete back-suction is realized by reducing the back-suction time, preventing the urea solution from evaporating (high temperature) and crystallizing, and blocking the nozzle; the back-suction control strategy is based on different application characteristics, ambient temperatures, and exhaust temperatures of the vehicle, and the optimization purpose is achieved through hierarchical back-suction strategies.

[0031] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be a limitation on the broad concepts of the application. Obviously, many modifications and variations of the specific exemplary embodiments described herein are possible in light of this disclosure, and it is intended that the scope of the application be limited only by the claims appended hereto and their equivalents. Examples of selected embodiments were chosen and described in order to best explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application. The application is intended to cover any adaptations or variations of the specific embodiments described herein.

Claims

1. A control system for reducing urea injection crystallization blockage, characterized in that, Comprise: a urea pump; a urea tank, whose liquid outlet is communicated with the liquid inlet of the urea pump through a liquid inlet pipe, and the urea pump extracts urea solution from the urea tank through the liquid inlet pipe; a nozzle, which is communicated with the liquid outlet of the urea pump through a jet pipe, and the urea pump can deliver urea solution to the nozzle for injection through the jet pipe; a return pipe, which is arranged between the liquid return port of the urea pump and the liquid return port of the urea tank; wherein the urea pump has a siphoning function, and the residual urea solution in the nozzle can be sucked back into the urea pump through the siphoning function of the urea pump through the jet pipe, and then delivered back to the urea tank through the return pipe; an ECU controller, which is electrically and data-connected with the urea pump, the urea tank and the nozzle, and can control the specific actions of the urea pump, such as liquid suction from the urea tank, liquid delivery to the nozzle, liquid return to the urea tank and graded siphoning from the nozzle; and an engine can bus, which is electrically and data-connected with the ECU controller, and through which the ECU controller receives information of the engine, and according to the injection demand of the engine, monitors the state of the urea tank, and issues injection instructions to the urea pump and the nozzle to execute injection actions; The control strategy for reducing urea injection crystallization blockage comprises: the ECU controller receives the demand of the engine through the engine can bus, and the ECU controller issues execution injection instructions to the urea pump and the nozzle as needed; and when the urea pump and the nozzle do not receive injection instructions or have completed the injection instructions, the judgment and waiting instruction state of siphoning work are entered; wherein the control strategy further comprises the control logic steps of judging whether to enter graded siphoning: according to the running characteristics or use scenarios of the vehicle, some intermittent vehicles are not entered into the graded siphoning strategy, and after completing a complete full siphoning strategy according to the siphoning time of 60s, the waiting instruction state of stopping work is entered; wherein at a higher temperature, a part of urea is reserved in the urea pipe, i.e. incomplete siphoning.

2. The control system to reduce urea injection crystallization plugging of claim 1, wherein, The control strategy further comprises: after entering the control logic of graded siphoning according to the running characteristics or use scenarios of the vehicle, the temperature judgment step is entered, when the environmental temperature is lower than-5℃, the full siphoning strategy is executed, the siphoning time is 60s, the residual urea is prevented from freezing at low temperature, the heating thawing effect is affected, and even the injection device is damaged, and after completing the full siphoning strategy, the waiting instruction state of stopping work is entered.

3. The control system to reduce urea injection crystallization plugging of claim 1, wherein, The control strategy further comprises: after entering the control logic of graded siphoning according to the running characteristics or use scenarios of the vehicle, the temperature judgment step is entered, when the environmental temperature is higher than-5℃ and lower than 30℃, it is further judged whether the environmental temperature is lower than 150℃, when the temperature is less than 150℃, the full siphoning strategy is executed, the siphoning time is 60s, and the urea solution is prevented from evaporating under high temperature to block the nozzle.

4. The control system to reduce urea injection crystallization plugging of claim 3, wherein, The temperature judging step of the control strategy further comprises: when the exhaust temperature is greater than 150 DEG C, performing an incomplete back-sucking strategy, the back-sucking time being 20s, and after the above back-sucking strategy is completed, entering a waiting instruction state of stopping working.

5. The control system to reduce urea injection crystallization plugging of claim 1, wherein, The control strategy further comprises: after entering the control logic of the graded back-sucking according to the running characteristics or use scene of the vehicle, entering the temperature judging step, when the ambient temperature is higher than 30 DEG C, further judging whether the ambient temperature is lower than 150 DEG C, when the temperature is less than 150 DEG C, performing a complete back-sucking strategy, preventing the urea solution from evaporating and blocking the nozzle in the high-temperature condition.

6. The control system to reduce urea injection crystallization plugging of claim 5, wherein, The control strategy further comprises: after entering the control logic of the graded back-sucking according to the running characteristics or use scene of the vehicle, entering the temperature judging step, when the exhaust temperature is greater than 150 DEG C, performing an incomplete back-sucking strategy, the back-sucking time being 10s, and after the above back-sucking strategy is completed, entering a waiting instruction state of stopping working.

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